Merge commit 'ad273dbe5dba7bd0e901270464e25fc1f030a5b5' as 'backend/goldmark'

backend/goldmark/parser/link_ref.go

@@ -0,0 +1,164 @@
+package parser
+
+import (
+	"github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/text"
+	"github.com/yuin/goldmark/util"
+)
+
+type linkReferenceParagraphTransformer struct {
+}
+
+// LinkReferenceParagraphTransformer is a ParagraphTransformer implementation
+// that parses and extracts link reference from paragraphs.
+var LinkReferenceParagraphTransformer = &linkReferenceParagraphTransformer{}
+
+func (p *linkReferenceParagraphTransformer) Transform(node *ast.Paragraph, reader text.Reader, pc Context) {
+	lines := node.Lines()
+	block := text.NewBlockReader(reader.Source(), lines)
+	removes := [][2]int{}
+	for {
+		ref, start, end := parseLinkReferenceDefinition(block, pc)
+		if start > -1 {
+			if start == 0 {
+				ref.SetBlankPreviousLines(node.HasBlankPreviousLines())
+			}
+			node.Parent().InsertBefore(node.Parent(), node, ref)
+			for i := start + 1; i < end; i++ {
+				ref.Lines().Append(lines.At(i))
+			}
+			seg := ref.Lines().At(ref.Lines().Len() - 1)
+			ref.Lines().Set(ref.Lines().Len()-1, seg.TrimRightSpace(reader.Source()))
+			if start == end {
+				end++
+			}
+			removes = append(removes, [2]int{start, end})
+			continue
+		}
+		break
+	}
+
+	offset := 0
+	for _, remove := range removes {
+		if lines.Len() == 0 {
+			break
+		}
+		s := lines.Sliced(remove[1]-offset, lines.Len())
+		lines.SetSliced(0, remove[0]-offset)
+		lines.AppendAll(s)
+		offset = remove[1]
+	}
+
+	if lines.Len() == 0 {
+		node.Parent().RemoveChild(node.Parent(), node)
+		return
+	}
+
+	node.SetLines(lines)
+}
+
+func parseLinkReferenceDefinition(block text.Reader, pc Context) (ast.Node, int, int) {
+	block.SkipSpaces()
+	line, _ := block.PeekLine()
+	if line == nil {
+		return nil, -1, -1
+	}
+	startLine, _ := block.Position()
+	width, pos := util.IndentWidth(line, 0)
+	if width > 3 {
+		return nil, -1, -1
+	}
+	if width != 0 {
+		pos++
+	}
+	if line[pos] != '[' {
+		return nil, -1, -1
+	}
+	_, startPos := block.Position()
+	block.Advance(pos + 1)
+	segments, found := block.FindClosure('[', ']', linkFindClosureOptions)
+	if !found {
+		return nil, -1, -1
+	}
+	var label []byte
+	if segments.Len() == 1 {
+		label = block.Value(segments.At(0))
+	} else {
+		for i := range segments.Len() {
+			s := segments.At(i)
+			label = append(label, block.Value(s)...)
+		}
+	}
+	if util.IsBlank(label) {
+		return nil, -1, -1
+	}
+	if block.Peek() != ':' {
+		return nil, -1, -1
+	}
+	block.Advance(1)
+	block.SkipSpaces()
+	destination, ok := parseLinkDestination(block)
+	if !ok {
+		return nil, -1, -1
+	}
+	line, _ = block.PeekLine()
+	isNewLine := line == nil || util.IsBlank(line)
+
+	endLine, _ := block.Position()
+	_, spaces, _ := block.SkipSpaces()
+	opener := block.Peek()
+	if opener != '"' && opener != '\'' && opener != '(' {
+		if !isNewLine {
+			return nil, -1, -1
+		}
+		ref := ast.NewLinkReferenceDefinition(label, destination, nil)
+		ref.Lines().Append(startPos)
+		pc.AddReference(newASTReference(ref))
+		return ref, startLine, endLine + 1
+	}
+	if spaces == 0 {
+		return nil, -1, -1
+	}
+	block.Advance(1)
+	closer := opener
+	if opener == '(' {
+		closer = ')'
+	}
+	segments, found = block.FindClosure(opener, closer, linkFindClosureOptions)
+	if !found {
+		if !isNewLine {
+			return nil, -1, -1
+		}
+		ref := ast.NewLinkReferenceDefinition(label, destination, nil)
+		ref.Lines().Append(startPos)
+		pc.AddReference(newASTReference(ref))
+		block.AdvanceLine()
+		return ref, startLine, endLine + 1
+	}
+	var title []byte
+	if segments.Len() == 1 {
+		title = block.Value(segments.At(0))
+	} else {
+		for i := range segments.Len() {
+			s := segments.At(i)
+			title = append(title, block.Value(s)...)
+		}
+	}
+
+	line, _ = block.PeekLine()
+	if line != nil && !util.IsBlank(line) {
+		if !isNewLine {
+			return nil, -1, -1
+		}
+		ref := ast.NewLinkReferenceDefinition(label, destination, title)
+		ref.Lines().Append(startPos)
+		pc.AddReference(newASTReference(ref))
+		return ref, startLine, endLine
+	}
+
+	endLine, _ = block.Position()
+	ref := ast.NewLinkReferenceDefinition(label, destination, title)
+	ref.Lines().Append(startPos)
+	pc.AddReference(newASTReference(ref))
+	return ref, startLine, endLine + 1
+}